Difference between revisions of "Part:BBa K4223005"

Revision as of 17:30, 21 September 2022

Cas14a protein-coding gene

His-tag, also known as polyhistidine tag, consists of 6 to 10 consecutive histidine residues. The most commonly used His tag is the 6xHis tag with a molecular weight of 0.8 kDa. The tag is used for many recombinant proteins and can aid in protein purification, enabling researchers to extract target proteins from thousands of proteins in cells or cell lysates. The structure of the 10×His tag is small, so it is less likely to affect the function of the fusion protein, and larger tags are more likely to affect the function of the fusion protein.

Histidine (His) has an imidazole group on its residue, which can form coordination bonds with Ni2+, Co2+ and other transition metal ions and selectively bind to metal ions. These metal ions can be fixed on the chromatography medium with chelate ligands. Therefore, proteins with His tags can selectively bind to the media when subjected to metal ion chromatography, while other impurity proteins can not bind or only weakly bind. The HIS-tagged proteins bound to the medium can be competitively eluted by increasing the concentration of imidazole in the buffer, so as to obtain high purity HIS-tagged proteins

In this process, a small His tag is fused to the N-or C-terminus of the target protein so that it can be trapped by nickel or cobalt ions immobilized on various resins. However, background binding is likely due to the presence of His residues in mammalian and insect systems. Washing in 5-10 mM imidazole avoids this problem, but this washing may result in premature elution of the target protein.

Sequence and Features